These examples were insipred by the
VHDL Tutorial: Learn by
Example page which proposes that when students are first learning
digital design, students should not be initally be burdened with the
intricacies of the underlying hardware description language (such as VHDL
or Verilog) utilized. Rather, students should focus on understand the
components being modeled and be able to modify examples to achieve the
We can describe the following combinational circuits structurally, meaning that we build the following circuits by instantiating various components such as AND, OR, and NOT gates, then specifying the interconnections among them.
Alterntively, we can describe the combinational circuits behaviorally. In a behavioral description the circuits are described by spcecifying their response to the inputs, rather than their interconnetion among instantiated components. Note that only the code changes in these examples. The testbenches remain the same, and the simulation results should also be equivalent.
Common Combinational Components